[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: on-line fossil birds list
This seems to be wrong. Read Gao and Ren (2006). It argues
VERY convincingly for a Middle Jurassic age.
Interesting. Please send me the pdf.
I have only read a reply by He et al. (2005) to a critique of their 2004
paper. They defend their conclusion there (but don't mention the Tuchengzi
Fm anymore) and show evidence for contamination by older crystals.
Personally, I get the impression that the lateral correlation between almost
any two sites is deeply mysterious at the moment. No wonder -- the area is
vast and consists entirely of 1000 m high mountains.
"[...] He et
al. (2004) also claim that, contrary to Ren et al. (2002) and
Liu and Jin (2002), ¡°at the Daohugou locality, the fossilbearing
sediments are also found to overlie the Tuchengzi
Formation at a few sites¡±, but they have not cited the
coordinates of the sites where this occurs nor have they
documented this contact in a photograph of these sites."
Well, OK, but that doesn't mean the site doesn't exist...
He H[uai]y[u], Wang X., Zhou Z., Zhu R., Jin F., Wang F., Ding X. & A. Boven
(2005): Reply to comment by Liu and Liu on "^40Ar/^39Ar dating of ignimbrite
from Inner Mongolia, northeastern China, indicates a post-Middle Jurassic
age for the overlying Daohugou Bed", Geophysical Research Letters 32,
L12315, 3 pages
There's also a paper by these authors from 2006 on the age of the Dabeigou
Fm (Hauterivian-Barremian boundary), but there they don't mention the
Daohugou Bed much, IIRC. (The pdf of that one is on the laptop, so I can't
check right now.)